Electric switch



Oct 16,1928. 1,687,560

' J. D. HILLIARD ELECTRIC [SWITCH 7 Filed April 6, 1923 Inventor: John D. Hilliard His Abbornes.

- Patented Oct. 16, 1928.

I 1,687,560 PATENT oerce.

. JOHN D. HILLIABD, OF SGHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELEGTBI Application filed A ril 6,

My invention relates to electric switches the sudden formation ofa considerable quan-- tity of gas, the amount of gas varying with the product of the resistance of the gas stream and the square of the current in the arc. In

an oil switch as ordinarily made there is a considerable air spaceimmediately above the surface of the oil, whichspace acts as a compi'ession chamber in which the gas generated is compressed momentarily and from which it escapes through the space between the top edge of the tank and under side of the cover or through aso-called mufller or separating chamber if the joint between the cover and tank has been made tight. The pressure within the air space when interruption of a current is made depends upon the quantity of gas generated, the rate of generation, the area for escape and the temperature of'the escaping gas. Whether or not the gas 'is.

ignited at its escape depends largely upon its (3 SWITCH.

1923. Serial No. 630,328.

My invention willbe better understood by reference tothe accompanying specification and drawing and its scope will be pointed out 7 in the'appended claims.

. .Alth'ough I have chosen to illustrate my invention as applied to an oil switch having a plam break, it is to be understood that it is by no means limited to a switch in which the insulating fluid is oil nor to a plain break switch but is equally applicable to switches employ ing insulating. fluids other than oil. and to other forms of switches, for example, those avmg explosion chambers.

Referring now to the drawing, 1 represents the switch tankwhich maybe of any desired shape and which is filled with insulating fluid 2, such as oil to the level indicated by 3. The cover ring 4 fits the top of the tank and is clamped thereon by the rods 5 having nuts at opposlte ends to engage respectively the cover plate 6 seatingon the cover ring 4 and the bar 7 beneath the tank. A pair of insulator bushings 8, 8 extend through openings in the cover plate 6'and support at their-lower ends the stationary contacts 9,9 of the switch. The movable contacts of'the switch are carried at opposite ends of the bar 10 to which. the opertemperature and both from the standpoint Ming rod 11 is attached.

of ignition and pressure it is desirable that the gas be cooled as much as possible and escape through as large an openingas possible in order to keep down the pressure in the tank. .It is desirable to prevent the ejec-r tion of: the gas and oil into the roomv and also to prevent the plugging of the vent opening by a slug of oil which, in the ordinary switch, frequently happens because the vent pipe being filled with. oil, can not quickly discharge the gas and as a result the tank pressure rapidly rises. j 7

An obj ect of my invention is to provide an improved switch which will have a very low' vide a switch in which the gas generated may escape with comparative freedom but in so 'fescaping shall be cooled below'the'point oxfignition. Further objects are to cool and impede the flow of oil'eiected with the hot gases and to reduce the pro ,ability of an ignition'of 7 gas due tdstatlc sparks.

The cover ring 4 which is shaped to conform to the shape of the tank is formed with groove or channel 12 for receiving the upper edge of the tank and in the bottom of this pressure. Upon the inwardly extending flange 15 of the cover ring 4; there is built upthe gas and oil cooling structure. This com: prises a series ofthin metal plates 16 spaced at distances approximately equal to their thickness. These plates may be made in the .form of rings 'which may be separatedby spacing washers 17 however it ;m ay be preferred to build up the structure from sets of straight or curved plates only, in which case i the ends of the plates of one set overlap and are interleaved with those of the adjoining setsan'd serve, to space the same. A plate 18 j and the whole is shown firmly securedtq the covers,the top of the structure thus formed "cover ring by means of bolts".19 which pass through the plate 18, the .thin'metal'plate's 16 and spacing washers 17 and which screw into the cover ring 15. The plate 18 has a central opening for receiving the operating rod 11 and a pair of opposite openings for receiving v the metallic supports 20 for the insulator bushings. These supports are bolted against the under side of the cover plate 6 and are provided with shoulders 21 for engaging the top face of the plate 18.

An additional means for separating the oil and discharged gas is shown attached to the outlet pipe 22. This means comprises two caps 23 separated by a pipe 24:, and enclosing two inverted caps 25 and 26, the former being supported by a spider 27 while the latter is supported by a spider 28. A parti tion 29 has a short pipe 30 extending through its center and on this partition as well as on the lower cap '23 is a layer of gravel 31 which may be held in place by wire mesh. Pipes 22 and 30 are each provided with a number of openings as shown for permitting the return of oil to the tank. From the upper cap 23 the gas may be piped to any desired location. By'the above described apparatus it will be apparent that excessive pressure in the tank due to the sudden generation of gas at the switch contacts will be avoided by the passage of the gas through the many openings between the plates16 and into the expansion chamber above. While the aggregate cross sectional area of these openings is amply suflicient to relieve the tankof destructive pressures the openings themselves are so narrow and are otsuch a depth that the in candescent gases in passing therethrough become cooled below the point where they could cause a secondary explosion in'the expansion chamber. The explosive effect of the gasformation' tends to .carry quantities ofoil with the gas in a more or less finely divided form. The plates 16 serve-to cool this oil and chamber.

is forced through .betweeuthe plates 16 will to hinder its passage into the expansion The greater partof the, oil which collect in the bottom of the chamber and find its way back between the plates 16 to the tank. Any oil remaining in the gases discharged from the expansion chamber will be strained out by the baflies and gravel separating means shown attached to the outlet pipe 22.

By the use of metallic supports 20 for surrounding and supporting the bushings 8 where they pass through the expansion chamber static sparks are prevented'from occur ring in this chamber which sparks migh cause the explosion of gas therein. 7

While I have described only one embodiment of my invention, I do not wish to be limited to the particular form shown and described as it will be apparent that many modifications therein may be made within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. A switch of the fluid break type comprising atank, relatively movable switch contacts mounted in said tank beneaththe level of said fluid, a cover for said tank forming an expansion chamber, and means comprising a plurality of superposed spaced plates carried by said cover above the level of the fluid for permitting the free escape of the hot gases formed by the are between said contacts and for cooling said gases below their ignition temperature before entering the expansion chamber.

' 2. A switch comprising a tank adapted tocontain an insulating fluid, a cover for said tank forming an expansion chamber for the gases formed in said tank, said cover having an inwardly extending flange portion, a

'series of alternately arranged plates and spacers, a cover plate for said series of plates and spacers, and means for clamping said cover plate, said plates and said spacers to said flange.

3. A switch of the fluid break type having an expansion chamber for the gases evolved, insulator bushings -extending therethrough, means for cooling said-gases below their ignition temperature before ,they enter said chamber and means comprising a metallic covering for the bushings for preventing the occurrence of static sparks in said chamber. 34. A? switch of the fluid break type comprising a casing forming an expansion chamber for-the gases evolved, insulator bushings passing through said chamber, means for cooling said gases below their ignition temperature before they enter said chamber and means surrounding those portions of said bushings passingthrough said chamber and connected to said casing for preventing the formation of static sparks in said chamber.

In witness whereof, I have hereunto set my hand this 5th day of April, 1923.

JOHN D. HILLIARD. 

